One of the most common firearm platforms currently in use forms the basis for the military M-16, M-4, civilian AR-15, and a plethora of related firearms. One of the most convenient aspects of the AR platform family is that the parts and pieces can be mixed and matched to produce a wide variety of firearms having different capabilities, different appearances, and even different calibers.
FIG. 1, labeled as “prior art,” illustrates an M16 type firearm 101 with mounting rails 106. The specific rifle is a flat top model having a mounting rail 106 on the upper receiver 102 as well as the four on the handguard 105. As is standard for M16 type firearms, the handguard 105 is attached to the firearm by being pushed into a front handguard cup 104 by a delta ring 103. The illustrated handguard 101 has four non-powered mounting rails 106 of which three are visible. A number of accessories have been developed to attach to small arms by way of mounting rails 106. The mounting rails have recoil grooves that help lock accessories in place and help users attach accessories in repeatable positions. Note that the term “firearm” used here and throughout this document is intended to include firearm replicas. In general, firearm replicas are toys or models that look substantially like fully functioning firearms and are designed to accommodate the same firearm accessories as those used with fully functional firearms. As such, FIG. 1 can also be a picture of a firearm replica. Certain M16 type firearms have “free floating” handguards that do not have a front handguard cup 104 or delta ring 103 but instead are clamped or bolted onto the firearm where the barrel is attached to the upper receiver.
FIG. 2, labeled as “prior art,” illustrates a handguard 201 with key lock mounting points 202 and a mounting rail 106. Two types of firearm accessories can be attached to the handguard of FIG. 2. One type is accessories for Picatinny rails that are clamped to the rail 106 and that often interface with the recoil grooves in the mounting rail 106. The second type of accessory is those that attach to the key lock mounting points 202. The keylock mounting points in FIG. 2 are “keyhole shaped” in that they have a larger round hole with a rounded slot extending outward. Other handguards have keylock mounting points that are not keyhole shaped but instead are slots that typically have rounded ends or rounded corners.
FIG. 3, labeled as “prior art,” illustrates three keylock mounting points 302 as viewed from the underside which would also be the inside of a keylock mounting system 301. The illustrated keylock mounting points are keyhole shaped with a larger round section 303 and a longer slotted section 304 extending out from the round section 303. The illustrated slotted section 304 has an angled inner surface 305. Other keylock mounting points do not have an angled inner surface 305, round section 303, or either.
FIG. 4, labeled as “prior art,” illustrates a cut view of the keylock mounting point of FIGS. 2-3. FIG. 4 provides a more detailed view of the angled inner surface 305 of a slotted section 304.
Keylock mounting points are advantageous because they are lighter than mounting rails but they experience difficulties because it can be more difficult to mount accessories to keylock mounting points than to mounting rails. Systems and methods for improving keylock systems for firearms are needed.